High GPU usage with glx backend and frame-opacity <1

[ntippie]

Platform

GPU, drivers, and screen setup

Nvidia RTX 3090 nvidia 550.54.14 single screen

Environment

bspwm, polybar

picom version

11.2

Steps of reproduction

$ nvidia-smi --query-gpu=utilization.gpu --format=csv,noheader
6 %
$ picom -b --config /dev/null --backend=glx --frame-opacity=1
$ nvidia-smi --query-gpu=utilization.gpu --format=csv,noheader
14 %
$ killall picom
$ picom -b --config /dev/null --backend=glx --frame-opacity=0.95
$ nvidia-smi --query-gpu=utilization.gpu --format=csv,noheader
50 %

Current Behavior

High GPU usage when using glx backend and frame-opacity <1. Recorded GPU usage was ~5x higher than when using frame-opacity=1

Workaround

frame-opacity=1

[ntippie]

Likely duplicate of #892